Re: [MiNT] update:WRITE_BOOT,ALLOW_TRP_CHG

[Jo Even Skarstein <joska@online.no>]

On Sun, 2012-10-07 at 12:09 +0200, Helmut Karlowski wrote:

> That's right. You can check that for example with cygcheck -k.
> 
> I get nothing when pressing the 5th key. So I have a good keyboard with 4  
> possible keys ;-)
> 
> But modifiers don't count, it's the same with 3 additional modifiers.

If you're talking about PS/2 keyboards then this is not a general rule.
It's probably just the strategy implemented in this particular keyboard
controller to handle ghost keypresses. It can not be predicted or
prevented by software on the host computer, atleast not without
intervention from the user.

As a general rule: PS/2 keyboards handles infinitely simultaneously
pressed keys. You can press them all if you've got enough fingers. But
depending on the keyboard implementation not all of them will be sent to
the computer. You can also risk that keys that are not held down will
generate "key down" events (ghosting). This same happens with the Stacy
keyboard too, and IIRC the TT/MSTE-keyboard.

USB HID keyboards are a different story. This protocol limits the number
of simultaneously pressed keys to six, plus modifiers. But ghosting can
occur with these keyboards as well.

Jo Even